504 SC'IENTIFIO RECORD FOR 1884. 



amount of the soluble gun-cottoD. Tlie jelly is very insensitive to blows, 

 and is not easily exploded, requiring a very powerful fuse, and is not 

 injured by water. It is said to be 75 i)er cent, strouger than dynamite, 

 and it is very free from liability to accident or injury in use or trans- 

 jjortation. On the other hand, its stability is questioned. Geueral Abbot 

 fouud that samples underwent spontaneous decomposition, separating 

 into cellulose and free nitro-glycerine, with a copious evolution of nitrous 

 fumes. 



Sir Frederick Abel, chief of the chemical bureau of the Woolwich 

 Arsenal, had a miraculous escai^e from death early in March, 1884. 

 He was barely ninety feet from the place where 1,000 kilograms of gun- 

 cotton accidentally exjiloded with terrific violence; he was knocked 

 down by the concussion and injured in several places by Hying missiles, 

 but in no wise dangerously. Sir Frederick ascribes his wonderful escape 

 to the fact that a strong wind was blowing at the time from him to- 

 wards the scene of the explosion. {Munroe's Rotes on the Literature of 

 Explosives^ No. VI.) 



Toughening Gold and Silver in the Gritcible. — Dr. James C. Booth, of 

 the United States mint, Philadelphia, describes a general method of 

 refining gold in the crucible as practiced in the mint. Some brittle 

 gold, having been accidentally melted with a quantity of well-refined 

 and tough gold, was found to have rendered the whole mass very brittle, 

 with a highly crystalline fracture, and therefore useless for coinage. To 

 avoid loss of time and greater cost of refining by acid, it was toughened 

 wholly by fluxing. This was accomplished on 75,162.55 ounces (5,154 

 pounds avoirdupois) in one and a half days, at a trifling cost, and with 

 scarcely apparent loss. The 75,000 ounces were divided into fourteen 

 melts of about 5,400 ounces each, and each melt was separately tough- 

 ened. The ingots, easily broken into pieces by striking them on the edge 

 of a wooden box, were put into the crucible with soda ash and anhydrous 

 fused borax, in the ratio of 1 or 2 ounces to a melt, until the crucible 

 was nearly full. It then appeared as a quiet mass of metal covered 

 with a rather viscid slag, disposed to swell and puff. A few crystals of 

 saltpeter, say 1 or 2 ounces, were then dropped successively into the 

 center of the metallic surface, and, as they melted, their spreading out 

 over the whole surface was aided by the concentric motion of the bot- 

 tom of a small crucible. The moment the visible oxidizing action began 

 to slacken the melter skimmed off by a small black-lead dipping cruci- 

 ble the fluxed matter, as rapidly as was consistent with the care neces- 

 sary to avoid taking up metal. The remainder in the melting-pot 

 was the toughened metal. The points to be noted are (1) that one 

 part of foreign matter sufiflced to impart brittleness to 75,000 parts of 

 good standard gold ; (2) by a slight oxidizing process the matter causing 

 brittleness was removed with no appreciable loss of gold ; (3) moreover, 

 the ratio of copper remained constant after the fluxing; (4) the tough- 



